All-Optical Measurement Of Vertical Charge Carrier Transport In Mid-Wave Infrared Inas/Gasb Type-Ii Superlattices

Time-resolved differential transmission measurements were used to investigate vertical charge carrier transport in mid-wave infrared InAs/GaSb type-II superlattices (T2SLs). By optically generating excess carriers near one end of the mid-wave T2SL and measuring the transit time to a thin, lower-bandgap T2SL at the other end, the time-of-flight of vertically diffusing carriers was measured. Through investigation of both unintentionally doped and p-type T2SLs, the vertical hole and electron diffusion coefficients were measured to be 0.04 +/- 0.03 cm(2)/s and 4.7 +/- 0.5 cm(2)/s, corresponding to vertical mobilities of 665 cm(2)/Vs and 700 +/- 80 cm(2)/Vs, respectively, at a temperature of 77 K. (C) 2013 AIP Publishing LLC.